What to choose as visa type for tourist visa

[freak22]

Hi. I am applying for tourist visa for my sister(21yo) to come visit me here in US. While filling out DS160 and the new visa scheduling portal, I see that that are two options (B1/B2 and just B2) to choose from as visa types. I am confused on which one to choose because my parents recently got their tourist visa and visa stamp shows type as B1/B2. We applied through agency for them who are refusing to say what they chose https://vidmate.bid/ . Thanks in advance for the help.